Index: src/InitTweak/GenInit.cc
===================================================================
--- src/InitTweak/GenInit.cc	(revision 300d75b9c8dd241e0cb0107c7549e5c8400a1024)
+++ src/InitTweak/GenInit.cc	(revision 4e22d7d1996ed8014cd6c0cd585313d457912bbe)
@@ -187,4 +187,6 @@
 			// need to resolve array dimensions in order to accurately determine if constexpr
 			ResolvExpr::findSingleExpression( arrayType->dimension, SymTab::SizeType->clone(), indexer );
+			// array is variable-length when the dimension is not constexpr
+			arrayType->isVarLen = ! isConstExpr( arrayType->dimension );
 			// don't need to hoist dimension if it's definitely pure - only need to if there's potential for side effects.
 			if ( ! Tuples::maybeImpure( arrayType->dimension ) ) return;